2014年2月10日月曜日

Neural Computations Underlying Arbitration between Model-Based and Model-free Learning

Sang Wan Lee, Shinsuke Shimojo, John P. O'Doherty
Neuron, Volume 81, Issue 3, 687-699, 5 February 2014

Neuron誌より、同僚のSangWanの論文。「モデル・フリー学習とモデル・ベースド学習、どちらを使うか」をどうやって決めているのか?という話。

There is accumulating neural evidence to support the existence of two distinct systems for guiding action selection, a deliberative “model-based” and a reflexive “model-free” system. However, little is known about how the brain determines which of these systems controls behavior at one moment in time. We provide evidence for an arbitration mechanism that allocates the degree of control over behavior by model-based and model-free systems as a function of the reliability of their respective predictions. We show that the inferior lateral prefrontal and frontopolar cortex encode both reliability signals and the output of a comparison between those signals, implicating these regions in the arbitration process. Moreover, connectivity between these regions and model-free valuation areas is negatively modulated by the degree of model-based control in the arbitrator, suggesting that arbitration may work through modulation of the model-free valuation system when the arbitrator deems that the model-based system should drive behavior.

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